1. Field of the Invention
The present invention relates to a method and system of collecting and processing acoustic data. More specifically, the present invention relates to a method for estimating anisotropy of a subterranean formation.
2. Description of Related Art
To obtain hydrocarbons such as oil and gas, boreholes or wellbores are drilled through hydrocarbon-bearing subsurface formations. The drilling of horizontal or deviated wellbores can create some difficulties of downhole imaging due to bed boundaries or dipping beds that are encountered downhole. To overcome this problem three-dimensional borehole profiles have been developed. These three-dimensional borehole profiles can change direction along the way.
A well bore drilled through earth formations encounters various geological structures intersecting the borehole. Borehole acoustic measurements can be used to obtain an image of the formation structural changes away from the borehole provided that the acoustic wave phenomena in the near borehole region are properly understood and utilized. Downhole sensors can be provided with a downhole tool for measuring downhole conditions. The downhole tool can include a sonde insertable within the wellbore as well as any subterranean drilling devices. Also included can be apparatuses for detecting inclination. These measurements are useful to determine hydrocarbons and water presence proximate to the downhole tool.
Subterranean formations are typically not isotropic, i.e. do not exhibit the same properties in all directions. Accordingly these formations are referred to anisotropic. Thus acoustic waves that propagate through the anisotropic formations do not encounter consistent formation properties in all directions. Because of this inconsistency of wave propagation, traditional seismic processing provides limited useful results.